Since my last update we changed to a different treatment chemical to reduce the possibility of discolored water and it has worked very well so far. After the New Year staff is going to try a modification of the treatment process to better control discolored water during times when there is normally a problem so they will not have to feed as much of the chemical I mentioned above. This multiple-barrier approach should make it easier for the Operators to send our customers the highest quality water during those times.
There has not been much visible activity with the studies under way to support the request for a permanent modification of the release requirements in the Virginia Water Protection permit. The transect studies wrapped up a couple of months ago and the consultant began the modeling work to determine the effects of potential release flows on the downstream river. On January 19th and 20th the final field studies are scheduled to take place which will provide the final data for the modeling effort. The flows needed for those studies are significantly lower than the normal flows this time of year so staff will have to draw the reservoir down below the spillway before January 19th to provide the needed storage to hold the excess flows in the reservoir while the studies are under way.
This is my final update to the blog as I will no longer be the Executive Director after today. I close my time here with the words Red Skelton used to close all of his shows, Good bye and God bless!
The Appomattox River Water Authority was formed in the 1960s to own/operate a regional water supply and sell drinking water to the cities of Colonial Heights and Petersburg as well as Chesterfield, Dinwiddie and Prince George counties. The information below is updated frequently to communicate current information on Chesdin Reservoir and its environment.
Saturday, December 31, 2011
Thursday, November 10, 2011
ARWA Update
The reservoir level this morning was one-inch below (-1.0") the spillway of the Brasfield Dam. Since the hydro-electric plant is running they are releasing water for the downstream portion of the river. The most recent flow at the Matoaca gauge downstream was 568 cfs, or 367 mgd, which is equal to 4.3 inches of water flowing over the spillway.
In the Daily Data page of this blog I included the estimated inflow for yesterday from 2006 through 2011 using the current formula and the formula we were using last Summer (2010). The estimated inflow under the 1965 Hopewell Agreement is also included in that table. The inflow under the Hopewell Agreement is different than either formula under the Virginia Water Protection Permit (VWP Permit) because it is based on the average flow past the upstream gauge (Mattoax) for the past thirty (30) days. The maximum release required under the Hopewell Agreement is 155 cfs (100 mgd) while the maximum release requirement under the VWP Permit is 190 cfs (124) mgd.
The drought response triggers for November, based on days of storage remaining in the reservoir, are as follows: Voluntary (27.35 mgd) = -19 inches; Mandatory (23.85 mgd) = -92 inches; and Emergemcy (22.85 mgd) = -156 inches. This means that, if we need to call for restrictions this month we would use the fixed trigger levels of -12 and -72 inches rather than the -19 and -92 inches based on remaining storage in the reservoir.
In the Daily Data page of this blog I included the estimated inflow for yesterday from 2006 through 2011 using the current formula and the formula we were using last Summer (2010). The estimated inflow under the 1965 Hopewell Agreement is also included in that table. The inflow under the Hopewell Agreement is different than either formula under the Virginia Water Protection Permit (VWP Permit) because it is based on the average flow past the upstream gauge (Mattoax) for the past thirty (30) days. The maximum release required under the Hopewell Agreement is 155 cfs (100 mgd) while the maximum release requirement under the VWP Permit is 190 cfs (124) mgd.
The drought response triggers for November, based on days of storage remaining in the reservoir, are as follows: Voluntary (27.35 mgd) = -19 inches; Mandatory (23.85 mgd) = -92 inches; and Emergemcy (22.85 mgd) = -156 inches. This means that, if we need to call for restrictions this month we would use the fixed trigger levels of -12 and -72 inches rather than the -19 and -92 inches based on remaining storage in the reservoir.
Wednesday, November 9, 2011
ARWA Update
Today we started flushing of our transmission mains to remove any sediment or film that has accumulated or built up on the pipe walls since we flushed last Spring. We are doing this as part of changing the corrosion inhibitor we add to the filtered water here at the plant. These products bind up any remaining manganese to prevent discoloration of the water as it flows between our plant and your tap. These products also help protect the waterlines and storage tanks it flows through from corrosion. This is the first of several additional steps we are implementing or investigating to give our Operators the tools they need to remove manganese even after storm events. We will refill the storage tanks in our customers' distribution systems tonight so we can complete flushing our mains tomorrow and return our transmission system to normal function.
Monday, November 7, 2011
ARWA Update and IFIM Question
This past Summer the frequent storms helped keep Lake Chesdin filled most of the time also brought us increased manganese levels that had to be reduced to prevent discolored water. I am sure that most of you know we were not always 100% successful at doing that last Summer so we are working on several approaches to deal with manganese in the future.
In terms of raw water we are investigating the feasibility of aerating the reservoir near our intakes to discourage the growth of algae that can cause taste and odor issues and keep the manganese in a form that is more easily removed by our treatment process. We currently oxidize the organics in the raw water and we are installing a treatment point to further oxidize any manganese remaining after the settling basins.
After filtration we treat the water further to keep any manganese left from causing discolored water between our plant and your faucets as well as help prevent corrosion in any pipes it passes through. We are looking at alternative products to use that better serve those purposes.
Before we start feeding the first, and hopefully the last, alternate product we are going to flush any settled material from our mains so we start with the cleanest pipes possible. We flush our mains every spring before higher Summer demands can stir up discolored water so this will be the second flushing this year.
We hope these efforts will provide us multiple barriers to more effectively reduce the manganese that leaves this plant in the finished water. We will not need to use all of them all the time but they will be there to help us when we need them.
At the October 2011 ARWA Board Meeting, Mark Krueger, a resident of Dinwiddie County, asked for clarification about something he read in our IFIM Study Plan. His concern was about one of the species of concern that the Virginia Department of Game and Inland Fisheries (DGIF) included in the habitat suitability analysis of possible releases from the reservoir. He wanted to make sure this was not a new species that was not present in the river now. He also had questions about the amount of water required to provide suitable habitat for this species.
With the help of our consultant performing the IFIM study I shared the following response with Mr. Krueger:
- The speices in question, American Shad, has used the James River and its ributaries in the past but they are not capable of getting past dams or similar structures in the rivers if they lack fish ladders or other similar devices. DGIF has been working for years to restore American Shad to the James River and its tributaries by removing structures and providing ways for them to get past remaining structures. Those restoration efforts are working so DGIF wants to make sure American Shad are included in the habitat suitability analysis for the Appomattox River.
When I looked at the figure in the study depicting the preferred water depths for American Shad it also appeard to me that they needed deep water during their juvenile stage. I concluded they would live in the reservoir or in deeper portions of the rivers during that stage. The consultant explained to me, however, that the figure was intended to show that American Shad prefer water 1 to 2 feet deep during the juvenile stage of their life and the deeper water is less desirable.
I appreciate Mr. Krueger asking his questions so we had the opportunity to clarify the information presented in the Study Plan. We look forward to more exchanges of this nature in the future as the project moves forward.
In terms of raw water we are investigating the feasibility of aerating the reservoir near our intakes to discourage the growth of algae that can cause taste and odor issues and keep the manganese in a form that is more easily removed by our treatment process. We currently oxidize the organics in the raw water and we are installing a treatment point to further oxidize any manganese remaining after the settling basins.
After filtration we treat the water further to keep any manganese left from causing discolored water between our plant and your faucets as well as help prevent corrosion in any pipes it passes through. We are looking at alternative products to use that better serve those purposes.
Before we start feeding the first, and hopefully the last, alternate product we are going to flush any settled material from our mains so we start with the cleanest pipes possible. We flush our mains every spring before higher Summer demands can stir up discolored water so this will be the second flushing this year.
We hope these efforts will provide us multiple barriers to more effectively reduce the manganese that leaves this plant in the finished water. We will not need to use all of them all the time but they will be there to help us when we need them.
At the October 2011 ARWA Board Meeting, Mark Krueger, a resident of Dinwiddie County, asked for clarification about something he read in our IFIM Study Plan. His concern was about one of the species of concern that the Virginia Department of Game and Inland Fisheries (DGIF) included in the habitat suitability analysis of possible releases from the reservoir. He wanted to make sure this was not a new species that was not present in the river now. He also had questions about the amount of water required to provide suitable habitat for this species.
With the help of our consultant performing the IFIM study I shared the following response with Mr. Krueger:
- The speices in question, American Shad, has used the James River and its ributaries in the past but they are not capable of getting past dams or similar structures in the rivers if they lack fish ladders or other similar devices. DGIF has been working for years to restore American Shad to the James River and its tributaries by removing structures and providing ways for them to get past remaining structures. Those restoration efforts are working so DGIF wants to make sure American Shad are included in the habitat suitability analysis for the Appomattox River.
When I looked at the figure in the study depicting the preferred water depths for American Shad it also appeard to me that they needed deep water during their juvenile stage. I concluded they would live in the reservoir or in deeper portions of the rivers during that stage. The consultant explained to me, however, that the figure was intended to show that American Shad prefer water 1 to 2 feet deep during the juvenile stage of their life and the deeper water is less desirable.
I appreciate Mr. Krueger asking his questions so we had the opportunity to clarify the information presented in the Study Plan. We look forward to more exchanges of this nature in the future as the project moves forward.
Monday, October 31, 2011
ARWA Update
I will be out of the office tomorrow and will not have access to update the blog. On Wednesday I will start posting the November data here and the October data will be added to the historical data on the ARWA web site.
Last week a citizeen called looking for a depiction of the water cycle or hydrologic cycle. I sent her a depiction I found at http://ga.water.usgs.gov/edu/watercycleprint.html. There are numerous depictions of the hydrologic cycle available on this website if you need them. The U.S. Geologic Survey (USGS) is a great source of water related information and I highly recommend checking their website first any time you are looking for that type of information.
Last week a citizeen called looking for a depiction of the water cycle or hydrologic cycle. I sent her a depiction I found at http://ga.water.usgs.gov/edu/watercycleprint.html. There are numerous depictions of the hydrologic cycle available on this website if you need them. The U.S. Geologic Survey (USGS) is a great source of water related information and I highly recommend checking their website first any time you are looking for that type of information.
Friday, October 28, 2011
ARWA Reservoir Levels
Yesterday afternoon Dominion Virginia Power asked the hydro-electric facility to shut down while they began work replacing three storm-damaged power poles along Chesdin Road. When they tried to restart last night they were not successful and had to wait to make repairs this morning. Similar starts and stops of the hydro-electric facility for equipment issues is why the graph below of the downstream river flows for the last seven days has such large fluctuations in flow.
Thursday, October 27, 2011
ARWA Update
One of the reasons we started this blog is to provide information to interested citizens on a regular basis so I must apologize that I have not posted anything in 7 days.
Last Thursday afternoon was taken up with Board meetings for both Appomattox River Water Authority and South Central Wastewater Authority. Since then we have been working on selecting a replacement for the boiler that provides heat to one-half of the treatment plant, the Laboratory, and the Administration offices.
The third item we have been working on since the Board meeting is the evaluation of potential products to replace our current corrosion inhibitor. We determined the current product was not as effective as it should have been in removing manganese from our finished water during recent manganese events which contributed to some customers experiencing discolored water. Changing a treatment chemical begins with looking at lots of information to make sure you select a product as good as, and hopefully better than, the current product used. That selection is followed by a lot of testing and evaluation of results to confirm the water quality is improved before we purchase the required quantities of the product.
We are also exploring two other solutions to address the elevated manganese levels in our raw water that occur following storm events. I will describe them in more detail in future posts to this blog. We will implement all of them, if they work, as multiple barriers to manganese to ensure our Operators have the tools necessary to address that issue when it occurs. Changes such as these require attention to lots of details to ensure we deliver the highest quality water to our customers throughout the effort to make the changes.
If you momitor the lake level at your property, or monitor river flows below the reservoir, you have probably noticed there has been a lot of variation in both over the past week. These variations were related to equipment issues associated with the hydro-electric facility located at the Brasfield Dam. Even with these variations in flow we always satisfied our permit release requirements.
Last Thursday afternoon was taken up with Board meetings for both Appomattox River Water Authority and South Central Wastewater Authority. Since then we have been working on selecting a replacement for the boiler that provides heat to one-half of the treatment plant, the Laboratory, and the Administration offices.
The third item we have been working on since the Board meeting is the evaluation of potential products to replace our current corrosion inhibitor. We determined the current product was not as effective as it should have been in removing manganese from our finished water during recent manganese events which contributed to some customers experiencing discolored water. Changing a treatment chemical begins with looking at lots of information to make sure you select a product as good as, and hopefully better than, the current product used. That selection is followed by a lot of testing and evaluation of results to confirm the water quality is improved before we purchase the required quantities of the product.
We are also exploring two other solutions to address the elevated manganese levels in our raw water that occur following storm events. I will describe them in more detail in future posts to this blog. We will implement all of them, if they work, as multiple barriers to manganese to ensure our Operators have the tools necessary to address that issue when it occurs. Changes such as these require attention to lots of details to ensure we deliver the highest quality water to our customers throughout the effort to make the changes.
If you momitor the lake level at your property, or monitor river flows below the reservoir, you have probably noticed there has been a lot of variation in both over the past week. These variations were related to equipment issues associated with the hydro-electric facility located at the Brasfield Dam. Even with these variations in flow we always satisfied our permit release requirements.
Wednesday, October 19, 2011
ARWA Update
The rain we are receiving today has already arrested the declining river flows at the upstream gauges and should cause the flows to increase if it continues long enough.
Earlier this Summer we experienced a problem with taste/odor in our finished water followed shortly thereafter with a discolored water event. The taste and odor issue was caused by our response to a sudden increase in algae in the reservoir. We treated closer to the intakes than we normally do and we learned to monitor algae more frequently to catch future increases sooner so we can treat farther away from the intakes with less algaecide.
The discolored water was caused by manganese, which occurs naturally in the raw water and rises following a rain event. We conducted a study of alternative filter media in 2009 and 2010 to determine if it would remove manganese better than our current media. The results of that study show that we do not normally have enough manganese in our raw water to condition that media so it will work better than our current media when we have a manganese spike following a rain event. The consultant recommended some alternatives and we are working on a request for proposals to investigate one of those alternatives, in-reservoir aeration near our intakes. This alternative will take some time to implement. We are proceeding, however, with investigating two other alternatives to increase the number of barriers our treatment process will provide to reduce the manganese levels in our finished water. The first is to feed an oxidizing agent we already use at a second location during a manganese event. The other is an investigation of alternative corrosion control agents to deal with any manganese that reaches that stage of our treatment process. We will keep you posted on the results of all of these investigations.
Earlier this Summer we experienced a problem with taste/odor in our finished water followed shortly thereafter with a discolored water event. The taste and odor issue was caused by our response to a sudden increase in algae in the reservoir. We treated closer to the intakes than we normally do and we learned to monitor algae more frequently to catch future increases sooner so we can treat farther away from the intakes with less algaecide.
The discolored water was caused by manganese, which occurs naturally in the raw water and rises following a rain event. We conducted a study of alternative filter media in 2009 and 2010 to determine if it would remove manganese better than our current media. The results of that study show that we do not normally have enough manganese in our raw water to condition that media so it will work better than our current media when we have a manganese spike following a rain event. The consultant recommended some alternatives and we are working on a request for proposals to investigate one of those alternatives, in-reservoir aeration near our intakes. This alternative will take some time to implement. We are proceeding, however, with investigating two other alternatives to increase the number of barriers our treatment process will provide to reduce the manganese levels in our finished water. The first is to feed an oxidizing agent we already use at a second location during a manganese event. The other is an investigation of alternative corrosion control agents to deal with any manganese that reaches that stage of our treatment process. We will keep you posted on the results of all of these investigations.
Tuesday, October 18, 2011
Chesdin Reservoir Level Update
Now that river flows are declining following last week's rain event we are once again seeking the right release through the hydro-electric facility to take full advantage of the flow into the reservoir to generate power but not draw the reservoir down below the spillway. Yesterday's inflow, using the current formula specified in the Virginia Water Protection Permit, was 770 cfs (498 million gallons per day) which is equivalent to 5.5 inches of water flowing over the spillway. The flow past the Matoaca gauge at 9:45 this morning was 589 cfs (381 million gallons per day) which is equivalent to 4.5 inches flowing over the spillway yet this morning the reservoir level was 1.5-inches below the spillway on the dam. The operators of the hydro-electric facility are reducing their flow with the goal of maintaining the reservoir level at the spillway. They will continue in this mode until they need to drop below the minimum flow required to turn their turbine. At that point they will cease operating and water will resume flowing over the spillway.
Monday, October 17, 2011
Reservoir Update
The reservoir level recovered quite rapidly last Friday and we were able to close the cone valve around 2:00 p.m.. so all the flow would go over the spillway. The reservoir level continued to rise over the weekend. This morning he flow past the Matoaca gauge downstream, 1130 cfs, is the equivalent of a little more than 7 inches of water over the spillway. The actual flow over the spillway is only 2 inches because the hydro-electric facility is releasing the difference to generate electricity.
Friday, October 14, 2011
Reservoir Level Update
This morning the reservoir level was two inches below the spillway (-2 inches) which is two inches higher than yesterday morning. The consultant completed the IFIM studies they were performing this week shortly before noon yesterday so we resumed releasing flow based on the estimated inflow for the previous day. Yesterday's estimated inflow was 409 cfs (264 million gallons) which means we only have to release 190 cfs (123 million gallons) today. After subtracting an estimated 45 cfs for raw water withdrawals this still leaves 174 cfs (112 million gallons) that will be stored in the reservoir. This should raise the reservoir level about 1.5 inches today. Therefore the reservoir level should exceed the spillway level sometime tomorrow at the latest. Once water is flowing over the spillway the hydro-electric facility can resume operation and generate power with the water flowing to the downstream portion of the river.
Thursday, October 13, 2011
IFIM Update
Yesterday the consultant performing the field work collecting river dat for the IFIM study completed 8 of the 10 locations on the river. This morning they completed the remaining 2 locations and recently notified us that we can resume releasing the down stream flow required by the Virginia Water protection Permit and/or the Hopewwell Agreement.
Resuming the required releases means the reservoir level will stay where it is until the increased river flows from the rain that started on Tuesday reach the reservoir. The current flows past the Farmville gauge are greater than the highest historical flows recorded on this date in the past 84 years. Those flows will reach the reservoir in 2 to 3 days and fill the reservoir completely.
Resuming the required releases means the reservoir level will stay where it is until the increased river flows from the rain that started on Tuesday reach the reservoir. The current flows past the Farmville gauge are greater than the highest historical flows recorded on this date in the past 84 years. Those flows will reach the reservoir in 2 to 3 days and fill the reservoir completely.
Wednesday, October 12, 2011
IFIM Update
Yesterday the consultant completed the 150 cfs flow stage of data collection at the selected locations on the study portion of the river. ARWA staff reduced the release flow last night so the consultant could start on the 50 cfs flow stage today. This morning the reservoir level was already one-inch higher than yesterday morning. This level will continue to recover about an inch a day while this flow stage is performed. The rains today have increased the river flows at the upstream gauging stations. These flows will reach the reservoir in 2 to 3 days and should completely fill the reservoir after the current flow stage is completed.
Monday, October 10, 2011
IFIM Study Field Work
This morning the consultant performing the In-stream Flow Incremental Mthodology (IFIM) study needed for our application for a permanent modification of our Virginia Water Protection Permit, and the associated down stream release schedule, began the second and, weather permitting, third flow stages to collect data at the ten (10) transect locations. The river flow target for the second stage is 150 cfs (97 mgd) and the flow stabilized at 166 cfs (107 mgd). The estimated inflow to the reservoir today, based on the flow past the upstream gauges yesterday, is 231 cfs (149 mgd). The raw water withdrawals from the reservoir today are averaging in the low to mid forty million gallons per day which is approximately 65 cfs. This means the sum of water released for the IFIM study and withdrawn to meet customer demands equals the inflow and the reservoir level should not change much today or probably tomorrow. The inflow will not decrease significantly by the time the consultant completes the 150 cfs stage and we reduce the release rate to 50 cfs so the reservoir level will recover several inches while that stage is underway. The reservoir level will recover even more if there is much rainfall in the Appomattox River watershed tomorrow and Wednesday.
There is one more segment of data gathering for the IFIM study and that is referred to as a Demonstration Flow Assessment or DFA. The DFA is a team-based study used for portions of a river that cannot be evaluated using transects to measure the physical nature of the river at selected locations. In the case of our study the DFA will be applied to a highly divided portion of the river below the Abutment Dam. This study will be run at four (4) different flow rates (40, 80, 120, and 190 cfs have been suggested) which will take several days. Once the team members have been identified for this study the work will be coordinated between their individual schedules and ARWA's ability to control the river flows.
Once the field data collection is complete, that information will be used to determine the effects of various release flows on the aquatic habitat in the river as well as other beneficial uses of the river (including public water consumption and recreation). All of this information will then be evaluated and included in the proposed release schedule that the Authority will submit to the Virginia Department of Environmental Quality (DEQ) as part of the request for a permanent modification of ARWA’s Virginia Water Protection Permit 01-1719.
Any action the DEQ decides to take concerning our requested permit modification will be advertised for public comment, and possible public hearing, before the record can be considered complete and sent to the State Water Control Board for approval. We will use this blog, and the ARWA website, to keep everyone interested in this process informed of what is happening concerning our request.
There is one more segment of data gathering for the IFIM study and that is referred to as a Demonstration Flow Assessment or DFA. The DFA is a team-based study used for portions of a river that cannot be evaluated using transects to measure the physical nature of the river at selected locations. In the case of our study the DFA will be applied to a highly divided portion of the river below the Abutment Dam. This study will be run at four (4) different flow rates (40, 80, 120, and 190 cfs have been suggested) which will take several days. Once the team members have been identified for this study the work will be coordinated between their individual schedules and ARWA's ability to control the river flows.
Once the field data collection is complete, that information will be used to determine the effects of various release flows on the aquatic habitat in the river as well as other beneficial uses of the river (including public water consumption and recreation). All of this information will then be evaluated and included in the proposed release schedule that the Authority will submit to the Virginia Department of Environmental Quality (DEQ) as part of the request for a permanent modification of ARWA’s Virginia Water Protection Permit 01-1719.
Any action the DEQ decides to take concerning our requested permit modification will be advertised for public comment, and possible public hearing, before the record can be considered complete and sent to the State Water Control Board for approval. We will use this blog, and the ARWA website, to keep everyone interested in this process informed of what is happening concerning our request.
Friday, October 7, 2011
October 7, 2011 IFIM Study Update
Our consultant plans on performing the next two flow stages of the data collection for the IFIM Study next week (October 10 - 14, 2011). The two flow rates are 150 cubic feet per second (cfs), or 97 million gallons per day (mgd), and 50 cfs or 32 mgd. During these tests we need to control the flow released to the lower portion of the Appomattox River within 5 cfs of the target flows. Since we expect the natural inflow into the reservoir to be higher than 150 cfs during the study period next week we have to draw the reservoir level down below the spillway on the dam by approximately 3 inches to provide sufficient space in the reservoir to store the inflow that exceeds our required release amount. During the 150 cfs stage on Monday and Tuesday the release amount plus the amount withdrawn for treatment should be about equal to the inflow so the reservoir level should remain very close to 3 inches below the spillway. When we reduce the release amount to 50 cfs for the second stage the reservoir level should recover and may be full again when this portion of the study ends sometime next Thursday.
The operator of the hydro-electric facility at the Brasfield Dam completed the maintenance work on their facility this afternoon so they will release the additional flow needed to draw the reservoir down by Sunday evening for power generation. They require more than 150 cfs to generate power so they will have to shut down during the IFIM Study work next week and we will release the water during the study efforts.
The operator of the hydro-electric facility at the Brasfield Dam completed the maintenance work on their facility this afternoon so they will release the additional flow needed to draw the reservoir down by Sunday evening for power generation. They require more than 150 cfs to generate power so they will have to shut down during the IFIM Study work next week and we will release the water during the study efforts.
Wednesday, September 14, 2011
Further IFIM Study Information
Our consultant’s staff is on the river collecting the required data for the IFIM study at the ten (10) transect locations. Originally we planned to get the 50 cfs stage done this week. After Hurricane Irene and tropical Storm Lee left their mark on the watershed the consultant was unsure of what the river conditions would be at 300 cfs so they planned on getting the second stage, 150 cfs, done as soon as river flows dropped to that flow. It would not be possible to control the amount of water released for the study if the natural flow was greater than the targeted flow of 150 cfs or there wasn't sufficient storage volume below the spillway to hold the inflow that exceeded 150 cfs.
After working on the river setting up the transects the consultant concluded they could work safely at 300 cfs and suggested proceeding with that stage while river flows are still elevated rather than wasting the time, and the water, waiting another day or two for flows to drop to around 150 cfs. If it took more than 1 day for the flows to reach 150 cfs the schedule would have to slip to next week for the first stage of the field work. After estimating what the inflow would probably be based on yesterdays flows upstream I concurred with their suggestion and proceeded with the 300 cfs flow stage.
Today’s estimated inflow, based on the flow past the Deep Creek and Mattoax gauges yesterday, is 256 cfs using the new formula and 324 cfs using the old formula. If we release 300 cfs downstream and withdraw approximately 50 cfs for water supply, we would take out/release about 100 cfs more than the lower estimated inflow. One hundred (100) cfs equals 65 million gallons or slightly less than a one inch (1”) change in the reservoir level when it is nearly full. Given that inflow will decrease over the 2-3 days of data collection the reservoir level should not drop more than 6 inches, including evaporation, during this period. The remaining controlled release rates, 150 cfs and 50 cfs, should be less than the daily inflow and the reservoir should recover some, if not all, of the storage volume released during the 300 cfs stage of this study, even if we do not receive any of the rain forecast for tomorrow and Friday.
Tuesday, September 13, 2011
Update on the IFIM Study
The sub-consultant performing the field work for the above study started setting up the study locations along the river today. Originally the plan was to run the lowest flow study at these locations this week but the lingering effects of Hurricane Irene and Tropical Storm Lee have kept the river flows too high to run that stage at 50 cubic feet per second (cfs) or about 32 million gallons per day (mgd). The plan this morning was to set everything up and get started late today or first thing tomorrow morning after the flow was down to the second stage of 150 cfs or 97 mgd. After working in flows near 300 cfs all morning the consultant recommended taking advantage of the current elevated flows and run the highest stage which is 300 cfs or 194 mgd.
There was still a small amount of water coming over the spillway with the hydro-electric facility discharging 250 cfs through their facility so we concurred with the consultant’s recommendation. We have asked the operator of the hydro-electric facility to go back to discharging 300 cfs until Thursday afternoon when this stage of the study will be complete.
This release will draw the reservoir down more than if we only released the required amount under either our Virginia Water Protection permit or our agreement with the City of Hopewell. When this first stage of the study is complete on Thursday we will resume releasing the required amount. We anticipate the inflow will be sufficient to hold the reservoir level at that time steady or to cause it to rise slightly due to the still elevated inflow and more seasonal water demands.
If you have any questions about this study please contact me at (804) 590-1145 or by e-mail at dawson@arwava.org.
Wednesday, July 20, 2011
Lake Data
Lake inflows have fallen for the past 7 days and have not been enough to recharge the lake's volume since July 13th. The lack of rain and declining flows in the river and creeks have led to daily drops in the water level.
Water intake for processing has been higher in the few days to provide adequate intake for maintenance purposes. The water taken in above the level we will need to support community use will be returned to the river below the dam and credited against our mandatory release as they are not needed.
Water intake for processing has been higher in the few days to provide adequate intake for maintenance purposes. The water taken in above the level we will need to support community use will be returned to the river below the dam and credited against our mandatory release as they are not needed.
Data (direct paste)
Daily data as direct cut and paste from Excel
| Date | Lake Level (in) | Inflow | Inflow | Withdrawn | Released | ||||||
Mattoax | Deep Creek | Total | Mattoax | Deep Creek | Total | Matoaca | |||||
Month | Day | (cfs) | (cfs) | (cfs) | (mgd) | (mgd) | (mgd) | (MGD) | (cfs) | (mgd) | |
July | 13 | 2.9 | 164.0 | 43.2 | 329.8 | 106.0 | 27.9 | 213.1 | 51.0 | 431.2 | 278.7 |
July | 14 | 2.0 | 140.7 | 34.1 | 271.6 | 90.9 | 22.0 | 175.5 | 39.0 | 282.3 | 182.5 |
July | 15 | 1.6 | 126.6 | 29.0 | 237.9 | 81.8 | 18.7 | 153.8 | 45.0 | 185.4 | 119.8 |
July | 16 | 0.8 | 119.4 | 22.0 | 203.8 | 77.2 | 14.2 | 131.7 | 43.0 | 133.4 | 86.2 |
July | 17 | 0.2 | 114.6 | 16.5 | 178.0 | 74.0 | 10.7 | 115.0 | 43.0 | 138.2 | 89.3 |
July | 18 | -1.2 | 108.5 | 12.9 | 157.9 | 70.1 | 8.3 | 102.0 | 48.0 | 160.6 | 103.8 |
July | 19 | -2.6 | 103.3 | 10.6 | 144.0 | 66.8 | 6.8 | 93.0 | 47.0 | 162.4 | 105.0 |
July | 20 | -3.4 | 98.9 | 8.3 | 130.8 | 63.9 | 5.4 | 84.5 | 47.0 | 176.8 | 114.3 |
July | 21 | -4.2 | 95.8 | 6.7 | 121.5 | 61.9 | 4.3 | 78.5 | 0.0 | 145.8 | 94.2 |
Tuesday, July 19, 2011
Lake Data
Inflows continue to fall below the level we need to maintain the lake level (~285 cfs/180 mgd).
Monday, July 18, 2011
Lake Data
The table below shows basic lake level, inflows and outflows for the past 7 days.
Inflows have been dropping off and fall below the level where we are able to maintain the lake's current level and still meet our commitments.
Inflows have been dropping off and fall below the level where we are able to maintain the lake's current level and still meet our commitments.
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